Train control



Feb. l0, 1925.

N. c. l.. BROWN TRAIN CONTROL I Fed May 29, 1922.

2 Sheets-Sheet l /1 91 101 el L i U B71 T a J as* 101 231 5i 91 1 "nn-r IIIIIII ab.' 1o, T1925.

N. C. L. BROWN TRAIN CONTROL Filed May 29, 1922 2 Sheets-Sheet 2 l changing t other device so i Patented elia litt, i925.

ecrirenon .Application ler Meer 2B,

yTo all whom t may coince/rn:

Beit known that l, Nen C. l2. BROWN, e

'citizen olf/the United States et America, re

siding; at Scottsville, in the county of Mon.- roe and State of New York, have invented certain new and useful improvements in Train Controls, of which the following is e specification.

This :invention relates to trein control systems, and more particularly to i'neans for communicating control influences from the traekway to a moving vehicle..

ln train control nnd'cebsignaling sys#v tems, it is necessary to communicate suitable control influences from' the treckway to the moving; trains. Such control influences are preferably transmitted through an air gap, rather than by physical contact between devices on the vehicle and devices along the trackway, because among; other things vices melting physical contact weer away rapidly, and are apt to interfere with other objects on the train or vehicle. ln one particular type of system to which this invention more particularly relates, the control vinfluences are transmitted inductively by employing magnetic devices along the trackwey cooperating` with devices on Athe vehicle, the track devices being ofthe character con venicntly termed the inert type, that is, devices which do not require any `energy from a transmission line or from e track battery to put them in the lion-storming` or inactive condition. Such an inert element is desirable, because a source of energy along the tackwey is not only expensive, but is not .always reliable.

n the particular system above referred to, the track element comprises, a magnetic cdre which is located along the treclnvay and is ade )ted to influence a car element by )he reluctance of the magnetic circuitof said cai element, such change in reluctence` being; utilized, by electro-magnetic induction or otherwise', to nctuatc a as to obtain the desired cona trollingy inuence. When the track elements 'are located between the track rails, they can not project much, if any, the rails, otherwise they low parts et the rolling' lowestfpert of the f kept above thetcp of the above the top of nieylae strnclr by stock. Also, the element hes be rails, sons to clear thetrack rails et crossings, switches end the `more with e.

relay or like. -lhese y lirnitetions .incite it necessary/to wel throupgli'a reletively large air gap oit tivo or nere inches, this eir gap also varying@i somewhat es the Wheels et' the vehicle ,veer down. Variation in battery voltage, resistance ci the coils or windings ivitli temperature cliengeegend other conditions, alter the strength et tite innence com" innnicetct. ist different tim s by the saune 'ti-eck devices llnder ce in ndveree circuinstnnces, a talee controlling irrlr e tney be .received "with the arrangement ist de scribed, because other magnetic bodies, such es crossing rails, impede-Ance bonds, switch frogs end lie like, will elotend to reduce the reluctance oi the lern nt passing thereover and are ent vnit an influence, thereby bringe ,D i, in 'to a stop nnnecessmily.

ll/itlr the above endlotlier considerations in mind, one ci the principal ot, oit the present invention is to use a pluiielity of cer elements and trece: elements arranged in such a menner'on the cnr that, while these elements will be juxtaposed and communicate the desired control inm iiuence, track rails or like magnetic bodies on the track will not produce thc seine effect trol apparatus.

Other objects and advantages of the invcnflion will appear as the description progressesv ln describing' the invention. in detail, reference will be mede to the accompanying drawings, in `Which Figure l shows diegjrainatically the track way equipment embodying the present in- `cention, the parte and circuits beine; shown view et melting it easy to nndcrstend the nature :and molle of operation of the invention, than with the purpose oi illustrating` the exact construction prei'- erably ,employed in practice; l

lig. 2 is a sixnplilied and diagrammatic perspective view ol one forni ot cer-cerried equipment g lig. 3 shows modified :torni of cerrarried equipment; and

Fig; d is a diagrammatic vien' for teting explanation ci the invention.

The impulse trensrrrtting inea .s embody ingthe present nv.; tcn coin, eral, a pair ci treclr facili end en. the trecli;

del

law@

icc

lil-il assenso produce an action on the car under way dangerous tralic conditions which may be lined in any one ot the Well-known Ways to regulate and control the movement of the in the ugual pony, ODO lllOCl. Wlllll th@ ddjlcent ends of two other blocks ll and J being` shown. Since the parts associated with the various blocks are the same, `for convenience they will be given like reference characters with distinctive exponents. Each o the blocks is provided with a track battery 2, a trac.; rela-y 3, a line relay 4e, and suitable track equipment; for the train control system.

ll'vl'hile the system of train control embodying this invention may be used with or Without the usual ixed traclnvay signals of a block' signal system, in the particular arrangement illustrated, it is assumed that somo suitae' torni of a block signal system will be employed in conjunction with the train control system. Such arrangement is considered preferable on the theory that a train control system should be an adjunct to the block signal system and atlord a supplementary protection to tain movements afforded thereby, rather than a substitute.

lfn l. the usual fixed semaphore signal .S at the entrance to each block has been illustrated conventionally. These signals S may be of any Well-known type; and the specific construction and detailed operation ot such signals is :familiar to those skilled in the art. No specific operating mechanism for the slcjnals S has been illustrated, because suitable constructions are Well-known in the art and are no part of the present in Avolition, and further in order to omit untrack, and which are suitably conl cuit controllers 5 and 6, respectively, which .in circuit closing position only -When its sigstill further to a vertical, clear or 90 degree position,'ivhen the 90 degree control circuit is energized. i

Each signal S is provided with two cir- 7 are illustrated in accordance With established convention and are in practice operatively connected to the semaphore operating mechanism. The circuit controller 'is 7 nal S is inthe clear or degree position, and acts to connect the coils of the track elements T and U in a closed circuit of preferably low resistance when the semaphore is in its clear position.` The other circuit controller 6, as indicated by the arcuate segment, is closed in the caution and also in the clear position of the semaphore arm, and in all immediate positions, thus interrupting the circuit of the line relay 4: one 85 block in the rear and'putting that rear signal at caution when the signal in question is at danger.

Along the trackway are provided. track elements T and U which comprise U-shaped cores 8 of soft iron, preferably laminated, these cores being provided with enlarged pole pieces 9. These track elements are preferably positioned so that the legs fall on the leur corners ot a square, as shown. llach leg of the cores 8 is provided with a coil l0; and these coils l0 are so Wound `and connected that the voltages induced therein, by a change in this passing through the cores, will be cumulative or in the same direction. The effectiveness of these track elements 't' and U upon the car elements L and M may be controlled directly by a line or traclcrelay, or both, but I have illustrated them as beicontrolled by the circuit controller 5 of tra; adjacent corresponding signal S, whereby the coils l() of the track clements T and U will be open-circuited, or put in their influence transmitting condition, when 'the semaphore blade of that signal is 110 in either the caution or stop posiiton, or in fact in any other except its 90 degree position.

The intluence communicating means of this invention may be employed to set into operation or otherwise control anysuitable or desired ilorm ot cab signal or brake control device, depending upon the character of regulation ol' train movement it is desired to obtain, ln the car-carried equipment illustrated in Fig. 2, the train control device K has been shown in the form of an electro-pneumatic valve which may be used to vent the train pipe directly, or which may be used to control other train control apparatus which depends lor its actuation upon certain other conditions, such as the speed of the train, the brake pipe pressure, the position ofthe train in the block, and other factorscntering into the desirediegiii) ule tice. ce coe l oyieu metil the tlitlfereiice of pressure ou oppce,

titles el' the valve lies heen reduced to e emouuen, euch, for inste'nce, es shown' emilie@ cri ci lilik lll. Howe No. s, llovemher 12, 1919. This; e icerliielly hclcl cloeecl when the cole il. le en.ergii:cul eetl will open il this oleiicitl l1 ie iiiohfiehtarily ueehergized9 momentary dcehergizetion leaving the ve operi uriil reset, clue to the ica e ci the ve.n elieiilri he umleretooil that the construcoperation of the trein control de oet described, is merely illuetretive ie type et device which een he used 'for ce, for ihstence, oit automatically' e hr1/the pipe to produce en auto plicetion; end it should he l. that device will he eppro i izohetructefl to limit the amount oi Viijpfe reduction, prevent the engineer i. ecchergihgg and avoiding the hrelie icotioii enel otherwise conform with ugijiproveti cir breite practice. A Although the treni control device l they he cone cuctell to he operated directly hy inlluei ce receivctllrcm the treclrway, is prete controlled by e control relay lit. control relay ie flceigneil in accordance with oiiiiciplee familier to those Skilled, in the e ical art eo to he quick eating, chil in other respects operate to the heet advantage under the conditions hei'eiimlter explained.. Among other things, this relay is constructed orjmount/ed. in Some suitable manner, forming ioo part of the preeent invention, so as to'he 'protected from false operation by jar emi. vibretion. 'lhie control tel-ey in turnie preferably coiitrolleil4 hy tivo tlicrmioiiic or vacuum hulh emplillere 12 and .l5 ci the Welllmovfu ccmuoerciel type, commonly known enel conveniently tleeigneted. es euclions lhese ehrliche have heen (liegrammeticelly illustrated, and. have the usuel lements ll and ll`1 'iride Gf end @il mul plates enel lll eo clissposed that the foon legs fit every Se to epeeli the corresitaohding legs of the lThe secondery coil ie track elements miel U These eer ele ,ments may he magnetically connected, either hy e hack yoke es shown, or hy mounting theee ef .mente directly on the truck? cer treme or other Sup port which iscoiietructetl ole magnetic materiel. One leg (shownes the lei'thand leg) of the forward cer element L end the iliegohellv opposite leg' (shown 'the rightlieefl leg) ,the reerxverd car element M ere prov/i l with prima@ coils 18 and l5), reepecllvely7 which are connected in seentier so that when seid' coils are i, these legge will he meghetizecl 'with opposite peleritiee, that is, for exemple, the coil 18 will produce n north pole, While the coil 1S) will jcroluce e south pole. ln other worde, the umguetlc iiux in forward cer element lo produced by its energifted priumry coil 18 will he in one direction, While the i'lux in the following cer element M will he in the other direction.

'lille primary colle 18 end 19 ere connected in series with the trein control device l across the batteries B and C, With the fronecoutect oit the control relay R in the circuit. which may be traced es follows: beginning et the positive side of the battery C, wire 39, primary coil 18 of the cer element L, Wire 40, primery coil 19 ot the cer element lllj wire lll, winding l1 olf the trein control device lll, wire 42, iront coiitect et control relay R, Wire Lift, leech to ,the negative eide et the hatt-ery ll. lling, when the control relziy R is deenergzerl the treize control device l( will be opereted, enel further en interruption of the circuit through the primary coils 18 and 19, or the depreciation of the battery, .vill cerise the trein control device K tobe operated, thereby effecting en leutomatic check upon. theihteg'rity oi this circuit, The other leg et the cer element L is provided with e. eecouclery Windieg; and the other lc of the cer element M is Similerly provided with e eecoiitlery Winding 21. iiicluded in thegrid circuit of the eurlion. 12, this circuit heilig traced es follows:--etmti:og :it the positive side ci the battery ll, wire 32, secondary winding 20j Wire 33 to the grid of the eudioii 12, through the euclioh to its fiilement T3, back tc-thc ,negative side of the battery ll. The secondary coil 21 is iiioludctl in the gir-icl circuit of Athe other emilion 13, Seial circuit being traced as followezhstarting et the positive Side of the battery' ll wire 32, Wire flito the efrlG'l oi through theeuclion to ite to the negative side ci the battery ll.

Under normal conditiohs,`tl1et is, when a. vehicle provided with the caecarried equipment illustrziteilL in Fig. 2 isjtrevelilfig between control points aud ie not being inthe euclion 13,

filament E, back ino Sccoiulerv Winding 21,

known practice.

fiuenced by track devices, the parts and circuits will be in the condition shown in the drawing. The filaments F and F1 of the audions l2 and 13 Will be heated by the battery A, and the potential of the battery B will be impressed through the secondaryrfv winding QOAupon the grid G, andthrou h the secondary winding 21 upon the grid 1, thus reducing the resistance of the plate circuits, thereby causing a current to flow in the. plate circuit of each audion l2 and 13 of sufficient magnitude to maintain the control relay R magnetized to keep its 'front Contact 43 closed. These plate circuits may be traced as l'ollows beginning at the positive side ol the battery C, wire 35, winding of the control relay R, wire 36, wire 37 to the plate H of the audion l2, through the audion to its filament F through the battery B and to the negative side of the battery C; and another circuit beginning at the positive side of the battery C, wire 35,. winding of the control relay R, wire 236, Wire 38 to the plate H1 ot the audion 13, through the audion to its filament F1, through the battery B and back to the negative side ot the battery C.

Before taking up in detail the operation of the train control system, it is convenient to explain the operation and condition or" the trackway circuits, signals, and track elements under different traiic conditions.V For the sake of simplicity in illustrating the track- Way circuits, the batteries or other sources of current-for these circuits have not been shown, but Wires terminating at P and N indicate a direct connection to a battery, either local or over a common Wire, it being of course understood that the same or ditlerent batteries may be employed in the respective circuits in accordance with well- The control circuits for each signal, and the control circuit for the corresponding track elements are the saine, aild the description ott one will suiice for a If the block J is occupied by a train, the track relay 31 is robbed of its energizing current due to the -shuntin'g action oi' the wheels and axles of this train; and consequently this track relay drops its armature and opens both the l5 degree or caution control circuit and the 90 degree or; clear control circuit for the signal S1, thereby causing the signal to assume the Zero degree or danger position. The movement of the signal S1 to the horizontal or stop position opens the circuit controlled by the circuit controller 61, thereby deenergizing t-he line relay l at the signal S next .in the rear. The dropping ot the line relay l interrupts the 9() degree or clear control circuit for the signal S, causing it toassume its l5 degree or caution position. Thus, with atrain in the block J, signal. S1 is in theistop position and the signal S is in the caution position.

The coils l0 ol the track elements T and U of each block are included in a circuit which may be traced as follows :-conimencin r at the upper coil l() ol the track element T, wire Q3, lower coil 1U, wire 2l, circuit controller' 5 ot signal S, wire 25, lower coil l() ot track element U, Wire 26, upper coil 10 of track element U, and Wire 27. l/Vith the corresponding signal in either the caution or stop position, the circuit controller 5 is open, thereby opening this circuit including the coils 10 oi' the corresponding track elements 'l and U. ln other Words, the 'track cienients T and il are'in the acti-ve stopping condition at each caution or stop signal. lt will be obvious, however, that the control of these track elements may be modified so as to produce a stop control only at a stop signal, or only at a caution signal, the particular manner ol' control desired depending upon the type ot' train control apparatus on 'the train to be governed.

.Referring now to the operation of train control system, the normal condition of the car equipment while traveling between control points' under safe trailic cond ons has been previously pointed out. fissunie new' that the car, equipped as shown in Fg. with the various devices and circuits thereon in the. normal condition as shown, is approaching the track elements and 'il in their active stoikiping condition, Ll

their coils l() inan open circuit.. .e track elements 'l and U in this acti -topping condition constitute in effect what may be termed a dead magnetic yloop or pa "tial circuit; or, putting` it another way, th track elements serve to act as bridge ot' low reluctance for the lcores of the elements la and M as the car passes over said track elements, The eliect of thesettrack elements in their active stopping condition is to greatly reduce tlie.reluctance of the tial niagnetic circuit through the car elcn ,nts L and M; and this change in reluctance causes lirst an increase in the magnetic this or lines of force, produced by the primary coils i8 and 19, througl'i tlie'secondary coils 2.0 d 2l, as the car elements approach the track elements. As the car elements come directly over the track elements, the reluctance is a minimum, the total fuir: a maximum, and the rate of change ot' flux zero. IThus, there is induced in the secondary coils 2O and 2,1 a single cycle or' alternating current the car elements approach, pass over, and recede from the track elements. The voltage inducrd in the secondary coils 2() and 2lwill have a polarity or direction in the external circuit ot these coils depending upon the that withr lill) insonne manner in 'which these coils are connected into their respective circuits. llior ordinary conditions, the connections are preferably made so that the voltage ot the Wave or half cycle is in a direction to oppose the battery B; but other arrangements snol coinbinstions of circuits can be used. Tn. any event, during the passage ot the car clemente over the traclr elements in their sctivc stop ping condition` the voltage. of the battery B is ten'iporarily opposed by a voltage induced in the secondary coils Q and '21, thereby reducingl the ,grid potential oil the audions and in turn reducingI the plate current-e .Tt will be notes that thc normal energieingcurrent oli the relay lit fs in effect niadc up ot two parts, that @flowing in the biste circuit oithe snclion l2, and that flowing in the plate circuitoi? the auction i3. lPutting it -anotl'ier Way, the energizing circuit for the relay lt may be said to lieve two multiple bronches with an clectroresponsive device in cach brunch, these electro-responsive devices being' separately iiiiuencetl by' voltsgdchanges in the secondary' coils 20 and 2l. blow,l when the cai elements l) and lit Dess over the track elements T and ll, the voltage waves in the secondary coils and 2l are in time `phase, that is, rise and tall simultaneously, 'since the spacing of the cores ot the track elements corresponds with that oi the cores oi? the car elements. rThus,

the grid potentials the two audions l2 and l?) are siinnltnnconf y affected, cnil like wise tbe rcdnction in the. current flowing; in the tno plate circuits through the relay R occurs simultaneously. The various bsttery voltegcs, windings. resistanccs and de.- viccs. are selected and proportioned so that concurrent reduction in the cu t ncu'nially flowing; in the plate circuits inc audions. induced by the passage c. the car elements over their respective tinck clements. brings about a decrease in the totnl current through the i'elojv lit to a pointl be low the di'opaway or holdup value for said relay. so that the iatures o'l the relay is retracted by its bias.y opening; the circuit through the trein control device lil and settingi said device into operation,

The dropping oli the armatore oi" the rc lav "il is on momentary, and the train control device is ot co as 'o contin e in tmeiszti` desired co l over the tn .i to such momentary opening oi. its energizing circuit.; but since this end may be ol.

tained in various Ways, by thc provisionoli stick contacts and the lil-te, snob, foil instance, as shown in the application oi W.. il., ltlowc heretoiiore 'referred to, and since the particular structure o'f the train control clevice itself Alorlfns no part oiitjthc present ina vention, 'no attempt has been made show any specilic structure tor this purpose, or

the provisions that would be also required for restoring the train control device K, manually or automatically, to its initial condition after it has performed its desired function in controlling the train. It should' be noted that thel oar element L must pass over the track ellnent U before it reaches the track element T. Such passage of the car element L over the track element U pron (luces substantially the saine eect on the grid Gr of' the audion 12 as when. it passes over the track element T, that is,assuming' that the traiclr elements are in their active condition. Such influence moon the grid G causes an instantaneous decrease in current ilow through the relay lt. This drop in current does, however, not bring the current below the dropawny value, and there fore docs not cause the relay R to drop. A similar eilect is produced on the grid G oi the audion 13 when the car element M passes over the track element T after simul tance-us registration ol cnr elements L and M with tinck elements T and U respectively,A that is, when the car elements L and M recede from the track elements T and U after coopemtionV of these respective elements.

The foregoing operation occurs at each pair of track elements T and U which have their control circuits open. According to the particular arrangement of the traclrway circuits shown in Fig. l, such operation occurs at cach caution signal and also at each stop signal; but it is evident that by ap` propriete arrangement ol1 control circuits,

this stopping iniiucnce may be communicatcd at stop signals only or at caution signals only, or in fact at anywiesired control point along` the track Where there are no sinals. Similarly, track elements Without coils l0 may be located at any desired point along the track Where it is desired to communicate a stopping inucnce ior every train at ull times, such as at the approachxto a fixed hazard. These, and other adaptations of the invention., Will bc evident to those skilled in the uit and need not be specifically shown' and described. y

Assume now that the vehicle, equipped as shown in Fig. .t and with its parts in the normal condition illustrated, approaches a signal in thc clczu' or proceed position. Under these conditions, the control 'circuit foi.' the track elements T sind lll associated `with that signal is closed by the circuit controller 5, tliiercby placing the coils l0 ot said track elements in s closed circuit of low resistance. lin Fig. l, this 4circuit connection is shown as putting the coils l() of the two tract: elements lllancl il in series, lont the same result mayl be obtained by including' the coils of they respective track elements in separate closed circuits. In either case, the coils l0 ohthe track eleins,

1anl

ments being in a, closed circuit will have .a tendency to oppose any change in flux in a direction to create u magnetic field op- SLi posing the flux inducing that current. Consequently, as the car elements L and M pass over the track elements if and U with their coils in a closed circuit of low resistance, the quick change in 'flux through the 'secondary coil 20 and 21 does not occur, due to the fact that the coils 10 of the track elements oppose such rapid change of flux. Thus, the grid potentiels of the uudions 19 and 13, although simultaneously ail'ected, are not reduced su'liiciently to sillon1 the er* mature ot the relayv lt to drop.

One of the importent characteristics of the present invention resides in the provi' sions mede to avoid premature or false operation of the car equipment by magnetic bodies, such as track rails, ordinarily encountered along the track. lt will be readily seen that the stopping influence in the system of this invention is produced by the magnetic qualities of the track elements; and accordingly a stopping influence of the same cheracter is to a certain degree produced by the truck rails at crossings, switches, Water pans, and other magnetic bodies along the track. Such track rail-s and other magnetic bodies do not of course produce as strong an effect upon'the car equipment as the track ele ments, because the track elements are made of a ood quality of magnetic material, laminated to avoid iron losses, and have a cross section such as to make these track elements much better magnetic conductors than ordinary track rails or the like. lin addition to the superiority of the regular track elements in their effect upon the car equi nient7 according to this invention the particular arrangement of the track elements in connection with the arrangement ot the cer elements enables the track elements to produce an eifect far greater than can he produced by track rails or other magnetic bodies ordinarily encountered alongga rsilroad track.

To make clear this important cheracteristic of the present invention, it will be exploined how track rails extending transversely to the running 'rails having various angles fail to affect the relay R apprcciably. Referring to Fig. 4, assume that the car elo-- ments L and M7 traveling in the direction indicated by the arrow sp )roach and pass over the track rail of the rig t angle crossing, indicated by the line 50. This truck rail will. first complete the partial magnetic circuit for the car element L, and then for the car element M. if the car elements L and M are spaced apart a distance depending upon the range or zone Within which flux changes oc e essence cur in the secondary coils duc to the vcycle ot' voltage in the scconderj.' coil 20 before producing any voltage in the sccondury coil 21. In other Words. the track rail. 50 produces its effect upon the lending cur element L fully before affecting the trailing car element M. Consequently', the grid potential of the :iudion 12 is changed und returns to normal before the grid potential of the audion 13 is ail'ected. with the result that the relay R always has in it a current equal to the full current lthrough the plate circuit or' one audion7 together with the reduced current in the plate circuit oi1` 'the other nudion; and since, previously explained, the currents in the plete circuits must bc concurrently7 reduced to a predetermined low value in order to cause the rlay li. to drop, it can he seen that the truck rail 5G' does not produce such operation.

lf the track rails are disposed at en ingle to the running; rails. their enfect upon the car elements becomes less :is the truck rails hecoine more and more nearly parallel with the running rails, since such track rails present little more thun their Width :is a magnetic conducting# path for flux through the cores of the car elements. For exemple. reiferring to Figa 4.. :i track ruil disposed nearly parallel with the running rails und the direction ot movement of the vehicle. as indi cated by the line 51, adds `very little iron to the partial magnetic circ-nit through the cores of the two car elements L und lll'. so that there is produced Very little chungo in flux in the sccondmy coils. At muy he added that on account ol" the relatively lurlife :tir gap between the car elements und the truc Way bodies. Whether the regular track ments or crossing; rails. the inclusion a small amount of iron in the magnetic circuit of the car elements produces ncxligililo cect. the greater part of the reluctance of the magnetic circuit heinir duc to cir gzip. so that a smell uniount ci iron luis proportionally less eiicct.

ln any event. u truck ruil to c large extent. regardless ot its angular relation to the running rails, fails to iniiuence thc secondari' coils Q0 and 2l simultaneousiyv und to the same degree so as to produce the ncccsserv reduction in the energizing cm` nt of the relay R to cause its armature to on: p. l'on though there is a slight ovcrlappin;A in the voltagrc waves induced in the secondary coils 20 and 2l, their cumulative effect upon the energizing current of the relay il is hound robe less than iii thesc Waves are exactly in time phase, as in thc euse ot the regular track elements. For example, imagine a track rail disposed at about degirccs to the 'running rails. as indicated by the line o1,- in Fig. 4;, and Visualicing the position of ilus fl l) viously described, and is energized by the batteries B and. C.

ln this embodiment of the invention, shown in iig. 3, the relay R1 is so designed 5 that when the circuit through either of its windings i-5 or 4G is completed, the front contact 431 of the relay lil will be closed maintainingl the circuit of the train control device .l completed, and when the circuit through the other winding is completed the total ampere turns ot the relay R1 will be again as much more above the dropaway, thereby preventing the train control device K from applying the brakes or con- 1'3 trolling the train in any other manner if only one of the car elements is ailected at a time. The operation of this modified form oi the invention is analogous to the embodiment illustrated in 2; and detail description of the operation is believed unnecessary.

Some of the characteristic features of this invention., in addition to the protection against rail interference to which attention has been more particularly directed, it will be observed consistin the fact that the various parts and circuits are constructed in accordance with 'the closed circuit principle of failure on the side of safety, that the track vay devices require no energy to change the controllincl condition, and that. the System provides or the transmission of a con' trol influence from the trackway to moving -vehicles inductively through an intervening air gap and without physical contact in a thoroughly dependable manner. In explaining this invention, it has been shown and described in its simplest iorm and without the various adjuncts that could be employed in practice to advantage; and l desire to have it understood that the particular structure shown and described does not cover or exhaust the many adaptations and modifications oi the means for practicing this invenl tion, nor include the various additions and applications of the invention to a complete system oi train control..

What claim is z- 1. Car-carried apparatus for automatic train control systems comprising, a pair of electro-responsive devices, a third electroresponsive device, each of said pair of devices normally supplying substantially the same amount of current to the third electroresponsive device, the current supplied by each 'of said pair of devices being suiiicient to maintain said third electro-responsive device in its normal energized condition, 'ind eparate means for influencing each electro- GO responsive device of said pair.

2. Car-carried apparatus for automatic train control systems comprising, a car-carried core of magnetic material,` a primary coil. and two secondary windings on said i5 core. a. senarate electro-responsive device governed by each of said secondary windings, a normally energized control relay maintained energized by both of said electro-responsive devices, each of said devices supplying enough energy to said control relay to maintainit in its energized. position, and separate means for influencing each of said electro-responsive. devices.

3. Car-carried apparatus for train control systems comprising, a plurality of car elements magnetically connected by a yoke to form a core having four projecting legs, primary windings on diametrically opposite legs, and secondary windings for receiving influences on the other legs, an electro-responsive device adapted to be actuated when an influence is received from each of said secondary windings simultaneously.

4. A car-carried element for receiving inductive control influences from the trackway for automatically controlling a train comprising, a back yoke having four downwardly projecting legs, normally energized primary coils on two of the legs, and secondary coils on the other legs.

5. Car-carried apparatus for train control systems comprising. a magnetic body having two diametrically opposite extending poles provided with magnetizing windings, and two diametrically opposite extending poles disposed in a different vertical plane provided with secondary windings, and a train control device adapted to be actuated by currents simultaneously induced in both of said secondary windings.

6. Car-carried apparatus for automatic train control systems comprising, a back yoke having7` four downwardly projecting legs arranged to form a quadrilateral figure, primary coils on a diagonally opposite pair of said legs, and secondary coils on the other two legs.

7. Apparatus as specified in the preceding claim, wherein the primary coils are wound and connected to a source of energy in a manner to form magnetic poles o'f opposite polarity. ,v

8. Car-carried apparatus for autmatic train control systems comprising, a back.

yoke of magnetic material having four downwardly projecting legs forming a quadrilateral ligure, oppositely wound primary coils ontwo diagonally opposite legs, and 'oppositely wound secondary coils on the other two legs, and a normally energized train co trol device governed by said secondary coils and deenergized only when simultaneous influences of a predetermined character arc received by said secondary coils.

9. In an automatic train control system, the combination of a car element comprising a magnetic body of four-cornered configuration and having a downwardly projecting lleg at each corner, .primary coils on two diagonally opposite legs energized to produce `magnetic poles of opposite polarity, secondary legs on the other two legs each connected to control apparatus and adapted to transmit ythe proper control influence if 5 magnetically influenced from one but not the other of said primary coi-ls, a normally energized train control device adapted to be deenergized only when simultaneous control influences of the proper kind are transmitted 10 by both of said secondary coils, and traffic controlled trackway means adapted tolnaglf,A netically influence one of said secondary coils by one of said primary coils and th'ther secondary coil by the other primary coil simultaneously as the car element passes over said trackway means.

In testimony whereof I hereto affix my signature.

NED C. L. BROWN. 

